Off the top of my head without thinking into it too much...I love a good brainstorm ?
Prefilled injector data for most mainstream injectors at stock reg pressure.
Perhaps a fuel pressure offset table for guys running aftermarket regs at different/constant pressures. Could you do a fuel pressure input and have a variable speed pump control output?
You want one decimal place for spark as it is pretty common to use half a degree.
Would it be possible to have a wideband input, a desired afr map and some type of histogram to show the offset needed to achieve it along with influencing tables/scalars? Something similar for spark and knock would be good but I spose that is pretty standard. Being able to change the whole table by the logged offset, ala winlog/tewblog, would enable quick map adjustments.
You've already mentioned data tracing and highlighting every affected table/scalar. This will be awesome.
A basic zf tuning manual highlighting which shift tables need to be changed to increase pressure and shift speed/points for paying customers. On that topic perhaps varying degrees of prefilled zf tune that can be used at ones own risk.
We've already got reds and greens but perhaps a warning system for clearly incorrect or dangerous cell entries. Although there is a range for the cell, we already saw today that an incorrect entry can cause problems. This could be limited to (final?) spark, fuel and wastegate areas.
Basic stock tune upgrade wizard. Detect the pcm/tcm and providing everything is stock (confirmed by the tuner/customer), load a suitable tune from a higher powered car such as f6, sprint etc. This will help noobs upgrade safely, at their own risk of course.
Wideband input with throttle blade close function on lean out. This could be tuned with map vs afr voltage.
There's a few spelling mistakes in the software as well, not that I'm picking. I guess that's part of getting it polished.
Anyhow, hopefully there's something good in there.